In order:
Die, Cant clone from dead cutting, and No.
All plants have a life cycle, when you flower her you begin the end of the plants.
If left to grow, it will simple suck the nutrients out of the rest of the plant until it is dead, nad buds are drying on the stem
However if still in Veg, a plant can be left to grow vegetatively indefinitely.
You don't want to clone in flower either, but rather a few weeks before you sex the plant.
And no, your plants massive root structure accumulated through vegg and flower will do nothing but decompose under the soil once the main stem is chopped.
Cheers.